Opt out while you still can

By the way - opting out is a super pain in the ass. It took two hours of jumping through hoops (including a video conference) before I could actually opt out. They don't make it easy, by any standard.

They already get the credit at the END OF THE YEAR. Here, you are getting the credit monthly.

By the way, 300 x 6 is 1800. The tax credit at the end of the year is 3600. So there is still 1800 left over at the end of the year.

If you owe because you took the advance, you owe because you owe a tax liability. The early credit didnt wreck your taxes, you did.

https://www.irs.gov/credits-deductions/2021-child-tax-credit-and-advance-child-tax-credit-payments-frequently-asked-questions

The payments are just starting now, and will be monthly through the end of the year.

I pay attention to the annual tax code changes. Paying quarterly, it's important that I get everything correct or I end up making a huge payment at filing time.

Many, I'd wager most, don't pay close enough attention. At filing time. With all of the pandemic payouts the feds have been making, it's likely that the less attentive will not realize that they're eating away at the credit. At the end of the year, their $3600 credit is half what they expect and their deductions dont cover their liability - they will owe.